Overview

Over the years, turbine-bypass technology has advanced along with that of the power

industry. F turbine-bypass systems have grown in sophistication to enhance

operational flexibility and to protect power plant components during a variety of transient

modes. With more than 1500 bypass valves supplied over the last 40 years and a strong

worldwide service network, our leadership has been proven time and time again.

Turbine-bypass systems are not only essential for the flexible operation of large coal-

fired power plants but play an equally important role in advanced combined-cycle

power plants. Turbine-bypass systems permit operation of the steam-generator independently

of the turbine during start-up, commissioning, shutdown and load disturbances. This enhances

operational flexibility during transient operating conditions. As a result, startup and reloading

times are reduced. In addition, equipment life and overall plant availability are increased.

To achieve the desired results, turbine-bypass systems must be adequately sized to meet

the needs of transient operating modes. F can effectively support plant designers

and plant operators in selecting and integrating a bypass system into an overall plant

design. In addition to providing original-equipment, we have extensive experience in

integrating bypass systems into existing plants and in retrofitting existing bypass valves that

have failed in service. Our worldwide sales and service organization and local engineering

centers are ready to support customers in their evaluation and engineering efforts.

F turbine-bypass systems meet the requirements of all governing boiler and valve

codes, including ANSI, ASME, TRD and many others.

Examples of CCI/Sulzer Bypass Systems:

1967 RWE Frimmersdorf, Germany(combined bypass and safety function)

1975 TEAS, Elbistan A, Turkey(once through boiler)

1982 Chubu Electric, Kawagoe 1&2, Japan(ultra-supercritical plant)

1988 HIPDC Shidongku, China(supercritical power plant)

1991 Korea Electric Power Corp., Korea(twenty supercritical units, Poryong, Taean,Hadong & others)

1993 Shanghai Municipal Electric Power Bureau,WaiGaoQiao 1-4, China

1993 China Light and Power, Black Point, China(eight combined cycle plants)

1993 Kansai Electric, Himeji Units 1-5/1-6, Japan(combined cycle units)

1995 Shell Australia Ltd., Geolong Refinery, Australia(system redesign and valve replacement)

1996 VEAG, Schwarze Pumpe, Germany(supercritical, combined bypass and safetyfunction)

1965-98 Various plants, Japan(over 40 bypass systems)

1971-98 Neyvilly Lignite 1-3, NTPC Rihand STPP, NTPC Talcher,CESC Budge Budge and other plants, India(over 100 bypass systems)

1972-98 Various plants, China(over 130 bypass systems with all utilities)

1981-98 EGAT, Mae Moh 4-13, Rayong, Ratchaburi, Thailand(drum, combined cycle, and supercritical plants)

1988 Pacific Gas & Electric, Moss Landing, USA(supercritical, cyclic operation)

1990 New England Power Service Co., Brayton Point, USA(supercritical, cyclic operation)

WaiGaoQiao Power Plant, China

Heat RecoverySteam Generator

Deaerator

Steam Turbine

HP-Bypass

Gas Turbine

LP-Bypass

IP-Bypass

HP-SystemIP-System

LP-System

GT GIP LPHP

Typical combined cycle power plant schematic

Purpose

Faster Start-up and Minimized Thermal Stress

A good turbine-bypass system reduces start-up time under cold, warm, and hot conditions. The turbine-

bypass system provides continuous flow through the superheater and the reheater, and allows for higher

firing rates which result in quicker boiler warm-up. It also controls superheater and reheater pressure during

the entire startup, keeping thermal transients in the boiler to a minimum. Operating experience shows that

power plants equipped with F turbine-bypass systems experience reduced start-up times and

much less solid particle erosion of the turbine blades, reducing the need for expensive repair and replacement.

Temperature Matching

A F turbine-bypass system allows optimum steam to metal temperature matching for all start-

up modes. The boiler load can be selected to reach the desired superheater and reheater conditions

for turbine start. This results in reduced start-up time and extented life for main turbine components.

“F turbine-bypass systems are recognized aroundstartup, preventing needless energy loss, lengthening

Avoid Boiler Trip after Load Rejections

A fast-acting F turbine-bypass system allows boiler operation to continue at an optimal

standby load while demand for turbine load is re-established after a load rejection. The turbine

can cover house load requirements. Pressure and temperature transients invariably associated

with boiler trip and restart are avoided.

Eliminate HP-Safety Valves

A F HP-bypass valve sized for 100% MCR capacity can serve as an HP-safety valve

when equipped with the necessary safe opening devices. This eliminates the need for separate

spring-loaded HP-Safety valves, associated piping, and silencers and can save millions of dollars

in equipment and maintenance costs. Our engineering staff is qualified to review applicable codes

and system designs.

Preventing Energy and Feedwater Loss

Even when regulations require spring-loaded safety valves, a large capacity F turbine-

bypass system with fast acting actuators can avoid lifting of the safety valves and the resulting

energy and water losses under almost all upset conditions.

Typical coal fired supercritical plant schematic

Steam Turbine

RH-Safety Valve

DeaeratorPreheaterEconomizer

Evaporator

Superheater

Reheater

HP-Bypass

Condenser

LP-Bypass

p

p

p

T

T

SafetySystem

SafetySystem

HP-BypassController

HP IP LP G

LP-BypassController

SafetySystem

the world as the best turbine-bypass systems for fastertrouble-free plant life and increasing plant reliability.”

Sizing of the F Turbine-Bypass System

Turbine-bypass system sizing considerations must take into account all plant operating

conditions such as the number of warm starts, hot starts and requirements for house load

operation. Later in plant life, cyclic operation may become common. Sizing of low pressure

turbine-bypass valves must take into account the desired reheater pressure for turbine

start as well as condenser capacity.

F turbine-bypass systems are custom designed to meet the specific capacity

requirements of the individual plant. Capacity can range up to 100 percent of the maximum

continuous rating (MCR) boiler steam flow for the HP-bypass as well as for the LP-bypass.

Integrating Turbine-Bypass Systems

F turbine-bypass systems can be supplied for any type of fossil-fired power plant.

The schematics on pages 4-5 show the integration of a turbine-bypass system into a

combined-cycle power plant (CCPP) and a 500 MW fossil-fuel-fired supercritical plant.

The chart to the right shows a typical hot-startup characteristic for a supercritical, fossil-

fuel-fired, 500 MW unit using a F turbine bypass system. Forty minutes after

lighting the steam generator, the steam temperature is matched to the turbine metal

temperature. The bypass system flow rate equals the difference between steam-

generator and turbine flows. In this case it is 22 percent of full flow. The corresponding

steam-generator pressure is 30 percent of full-load pressure (80 bar [1160 psig] at 40

minutes compared to 260 bar [3800 psig] at full load).

The result is a required turbine bypass system capacity of approximately 70 percent

MCR at full load (percent-steam-flow divided by percent-pressure). Because of the

large bypass system designed into this particular plant, coal firing can be initiated

earlier, thus reducing the amount and cost of oil necessary in the start-up cycle.

minutes

%

100

100

50

50

0

Full LoadSynchr.

Pulverizers

Light up

0

˚C

500

400

300

200

100

0

barflowtemp press

S t e a m

Start-Up Time

300

200

100

4.2

4.1

3.1

2.42.3

2.22.1

1.1

1.1 Firing Rate2.1 Feedwater Flow2.2 Waterwall Flow2.3 Steam Flow (Superheater)2.4 Steam Flow (Turbine)

3.2

3.1 Superheater Pressure3.2 Reheater Pressure4.1 Superheater Temperature4.2 Reheater Temperature

Hot start of a supercritical 500 MW unit

“F has developed a wide range of technologies for

supplier of turbine-bypass systems, F supplies researched

Valves

Duty of a Turbine-Bypass System

The primary job of any turbine-bypass system is steam conditioning — high-pressure throttling

integrated with desuperheating. Bypass valves must be able to perform these functions

and achieve the desired pressures and temperatures without undue noise and vibration

and without destructive valve-trim wear. In addition, bypass valves must perform these

functions under severe temperature cycling.

Depending upon plant design, bypass systems must also perform additional functions

such as safe HP-bypass opening and LP-bypass closing for condenser protection during

transient operating periods.

F offers the advanced valve technology to meet these severe service

requirements. With its distinctive body design, F is recognized as the lasting

turbine bypass valve technology around the world.

Lower Noise and Vibration

Excessive vibration in a turbine bypass valve can break pipe hangers and shake

accessories off actuators, resulting in high maintenance costs and unscheduled downtime.

Using wave-principle theory, F developed the unique WING-type stem with

contoured cage design for use in high pressure bypass systems. Unlike conventional plug

designs, the WING-type stem has a specially contoured profile to produce wave

interference. This effectively “cancels out” some of the aerodynamic effects as they impact

valve parts. This design incorporates specially engineered channels that divide the steam

flow into discrete paths and increase generated noise frequency. This higher frequency

noise is more easily absorbed by the adjacent piping and results in noise-level reduction

of more than 10 dBA as compared to conventional designs.

F WING-type trim

valves, desuperheating, actuators and controls. As the original

and proven solutions to suit the needs of any type of plant.”

In addition, the WING-type stem with contoured cage creates a highly turbulent zone

immediately down-stream of the valve seat in drum and supercritical plants. This turbulent

zone is ideally suited for the in-body injection of desuperheating spraywater. Also, noise is

attenuated by water injection inside the valve. This valve design ensures that this turbulent

zone is removed from any valve surface to eliminate a source of vibration.

For installations requiring strict noise control, F offers a low noise DRAG® solution.

DRAG® solutions provide the lowest noise for any turbine-bypass available in the industry.

Noise generated by the valve can be kept to below 85 dBA throughout the entire operating

range without the use of back pressure diffusers and acoustic insulation.

CCI DRAG® Disk Stack

With their distinctive body design, F are recognized as the benchmark of

turbine bypass systems — Distinctive, Complete, Proud, Swiss — F

Thermographic analysis of a bypass valve during start-up showingcomplete water atomisation inside a F DRE valve

Thermally Efficient Design

F turbine bypass systems feature unique thermally efficient bodies designed to

eliminate the stresses from thermal transients associated with cycling duty. The body designs

incorporate thin-walled spherical sections to produce compact, strong valves that are

easily recognized as the distinctive F style.

Isolation Valves

Specifications often call for steam-isolation valves upstream of the LP-bypass valve

for condenser protection. F supplies LP-bypass valves which combine the

control function with a safe-closing function. However, if the specification requires a

bypass system with separate control and isolation valves for reasons of a different

plant safety philosophy, we an also supply steam isolation valves.

Reheater Safety Valves

F has developed many different

technologies for desuperheating. The

primary job for any type of desuperheater

is the complete evaporation of the

injected water — this must be

accomplished without any water droplets

hitting the pressure boundary walls of the

valve or downstream piping. Key factors

affecting desuperheater performance are

the degree of atomisation of the injected

water and the mixing with the steam, and

second, quick evaporation with proper

location and direction of the spray water

jet. Complete evaporation must be

attained before the first pipe bend to

prevent any erosion caused by high-speed

droplets contacting the pipe walls.

The degree of spraywater atomization

attained is determined by the relative

speed of steam flow to that of injection

water flow. Full atomisation is the result of

high water injection speed and injection

of the desuperheating water into a zone

of turbulent, high-speed steam flow. In

addition, factors such as accuracy of

controls, flow range and piping

arrangement can affect the quality of

atomisation. Finally, good atomisation can

only be achieved when the proper

spraywater valve is selected. A good

spraywater valve will have multi-stage

pressure letdown to eliminate cavitation

and trim erosion in order to maintain fine

temperature control at all steam flows.

F experience and technology

ensures the optimal solution of complete

atomisation every time.

In-Body Desuperheating

For HP bypass applications in a drum or

supercritical power plant, Frecommends in-body desuperheating.

In-body desuperheating makes the best

use of the principle of water injection into

a zone of high steam-flow turbulence. The

spraywater is fully atomised before the

steam exits the valve body, thereby

providing the shortest evaporation length.

In-body desuperheating provides the

best atomisation available.

Desuperheating

“The desuperheating function in a F turbine-bypass

and quick evaporation of the injected water without

Steam conditioning valve type DREusing inbody desuperheating technology

Proper design of in-body desuperheating

requires a detailed understanding of the

flow pattern inside the valve at all load

conditions. F has done extensive

research into these flow patterns, including

spraywater injection and atomisation with

the help of dynamic numerical calculations.

Optimum arrangement of the injection

nozzles, material selection, and shape

and hole pattern of the cage around

the injection zone is the result of this

extensive research.

F is the only turbine bypass

system supplier that has perfected in-body

desuperheating technology to provide

long lasting, fully integrated steam-

conditioning within the valve body. With

this technology, we recommend only a

very short straight length of piping

downstream of the valve. In addition,

piping material downstream of the valve

may be switched to carbon steel instead

of alloy material.

must provide for excellent steam and spraywater mixing

creating thermal stress that can cause system damage.”

Steam conditioning valve type NBSEusing spring loaded spray nozzles

Spring-Loaded Injection Nozzles

Spring-loaded nozzles are typically used for LP

bypass applications, but can be used in all

types of combined cycle power plant

applications. The atomizing principle of spring-

loaded injection nozzles is based on high-

speed injection. Due to the design of the

spring-loaded nozzles, a sufficient injection

pressure and injection speed exists at minimum

load. The injection speed results not only in good

atomisation but also in a sufficient penetration

of the spraywater into the steam flow.

In addition, the F spring-loaded

nozzle incorporates a unique swirl pattern

which provides rotational energy to the

spraywater over the entire range of flow

conditions. This insures an even distribution

which produces good mixing of steam and

spraywater with extremely good rangeability.

Ring-Type Desuperheater

For LP bypass applications, Frecommends separate desuperheating

downstream of pressure reduction. In a ring-

type desuperheater, which is used primarily in

drum and supercritical power plants, steam

turbulence is created by the shape of the

steam-flow. The steam velocity is increased by

a contraction of the flow path, and the

injection takes place where the flow path

abruptly expands. Mixing takes place in this

region of turbulence to produce the shortest

distance required for atomisation.

Ring type desuperheater EK

F DRAG® steam conditioning valve

using steam assisted STEAMJET desuperheating technology.

The desuperheater is also available as a separate

downstream component.

Steam-Assisted Desuperheaters

F has developed the STEAMJET

desuperheater for steam conditioning

applications requir ing the best possible

atomisation outside of the body. The

STEAMJET provides significantly better

atomisation than the ring-type and spring-

loaded nozzle desuperheaters currently

available in the industry. The design is

based on a combination of high-speed

water injection into a high-velocity , venturi

steam flow. The "compound swirl" nozzle

provides high injection speed while the

atomising steam provides a velocity which

is virtually independent of the main steam

flow. The spray pattern is centered in the

piping to produce even temperature

distribution at all flow conditions.

F STEAMJET produces the shortest

distance required for atomisation of all

downstream desuperheaters.

Sparger Tubes

F provides custom-engineered

condenser sparger (dump) tubes for the

introduction of steam from the bypass valves

to the condenser. These optional sparger

tubes are custom designed to meet the space

constraints of the specific condenser and to

protect the internals of the condenser.

As required, we will engineer the sparger tubes

to meet low-noise requirements.

Pneumatic actuator

Hydraulic power unit for a bypass system

Actuators and Controls

Reliable system operation is based on the proper

select ion and design of al l of the system

components . Using advanced technology

developed by F over years of testing and

experience, our expertise has produced the best

pneumatic and hydraulic actuation technology

in the industry.

Pneumatic Actuators

F pneumatic actuators feature a double-

acting piston designed to meet the application

requirements for stroke, speed, actuating force, and

positional accuracy. The actuator is equipped with

quick acting components to achieve stroke speeds

for bypass applications of one second.

F is the only supplier in the industry to provide

high speed pneumatic actuation with stable control.

Hydraulic Actuators

Hydraulic actuators are well suited for applications

requiring high force and high stroking speeds with

precise control. F provides the complete

system consisting of hydraulic cylinders, control devices,

positioners and hydraulic power units. The hydraulic

power units meet all safety requirements and consist

of a fluid tank, pumps, filters, accumulators, and the

necessary monitoring and controls.

“Turbine-bypass valves and their actuators and controls

must be matched for optimum system performance.”

Hydraulic actuator

F AV6 series bypass controller

Our hydraulic actuation systems and controls are

recognized as the original, long-lasting technology

for hydraulic actuation.

Safety Systems for HP Bypass valves

In countries where regulations allow the use of HP-

bypass valves as safety valves against superheater

overpressure, F can provide bypass valves,

actuators , and the necessary safety control

equipment. Safe trip devices can be easily mounted

on hydraulic actuators permitting the use of bypass

systems in place of safety valves. The complete safety

system has a type approval according to the

German TRD421 code.

F Turbine-bypass Controller

A well-designed bypass controller is important for

smooth plant operation, especially during plant

start-up, shut down, and load disturbances. We

have more than 25 years’ experience in designing

and supplying turbine-bypass controllers.

Our latest AV6 series turbine-bypass controller uses

advanced control strategies. The state controller

with observer (SCO) provides more precise control

than standard systems, thereby producing less thermal

cycling stresses on valves and pipings.

The AV6 series controllers can easily interface to any

boiler and turbine control system.

CCI World HeadquartersTelephone: (949) 858-1877Fax: (949) 858-187822591 Avenida EmpresaRancho Santa MargaritaCalifornia 92688 USA

CCI Switzerlandformerly SULZER THERMTECTelephone: 41 52 262 11 66Fax: 41 52 262 01 65P.O. Box Hegifeldstrasse 10CH-8404 Winterthur, Switzerland

CCI JapanTelephone: 81 726 41 7197Fax: 81 726 41 7198194-2, ShukunoshoIbaraki-City, Osaka 567Japan

CCI KoreaTelephone: 82 341 85 9430Fax: 82 341 85 055226-17, Pungmu-RiKimpo-Eup, Kimpo GunKyunggi-Do, South Korea

CCI UK Technology CentreNorth EuropeSharp StreetWorsley, ManchesterM2B 3NA, England

MC-310-10/98 310

“We Solve Control Valve Problems”Sales & Service Locations Throughout The WorldE-Mail: info@ccivalve.comWeb Site: http://www.ccivalve.com

Fa product of CCI

F are manufactured in a

state of the art facility centrally located in

Switzerland. We welcome you as a visitor

to our factory and beautiful country.